repl: don’t complete expressions when eval fails

Instead of changing the way “simple” expressions are detected,
switch to ignoring errors when completing. This approach is more
generic than the previous one from 0b66b8f2d, but also changes
the way errors are thrown when completing.

This reverts the code changes from commit 0b66b8f2d2.
The test case is left intact.

Fixes: https://github.com/nodejs/node/issues/6325
PR-URL: https://github.com/nodejs/node/pull/6328
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/repl.js

@@ -628,7 +628,7 @@ ArrayStream.prototype.write = function() {};
 
 const requireRE = /\brequire\s*\(['"](([\w\.\/-]+\/)?([\w\.\/-]*))/;
 const simpleExpressionRE =
-    /^\s*(([a-zA-Z_$](?:\w|\$)*)\.)*([a-zA-Z_$](?:\w|\$)*)\.?$/;
+    /(([a-zA-Z_$](?:\w|\$)*)\.)*([a-zA-Z_$](?:\w|\$)*)\.?$/;
 
 function intFilter(item) {
   // filters out anything not starting with A-Z, a-z, $ or _
@@ -806,7 +806,8 @@ REPLServer.prototype.complete = function(line, callback) {
           });
         }
       } else {
-        this.eval(expr, this.context, 'repl', function(e, obj) {
+        const evalExpr = `try { ${expr} } catch (e) {}`;
+        this.eval(evalExpr, this.context, 'repl', function(e, obj) {
           // if (e) console.log(e);
 
           if (obj != null) {

test/parallel/test-repl-tab-complete.js

@@ -3,19 +3,13 @@
 var common = require('../common');
 var assert = require('assert');
 var repl = require('repl');
-var referenceErrors = 0;
-var expectedReferenceErrors = 0;
-
-function getDoNotCallFunction() {
-  expectedReferenceErrors += 1;
-  return function() {
-    assert(false);
-  };
-}
 
-process.on('exit', function() {
-  assert.strictEqual(referenceErrors, expectedReferenceErrors);
-});
+function getNoResultsFunction() {
+  return common.mustCall((err, data) => {
+    assert.ifError(err);
+    assert.deepStrictEqual(data[0], []);
+  });
+}
 
 var works = [['inner.one'], 'inner.o'];
 const putIn = new common.ArrayStream();
@@ -23,13 +17,7 @@ var testMe = repl.start('', putIn);
 
 // Some errors are passed to the domain, but do not callback
 testMe._domain.on('error', function(err) {
-  // Errors come from another context, so instanceof doesn't work
-  var str = err.toString();
-
-  if (/^ReferenceError:/.test(str))
-    referenceErrors++;
-  else
-    assert(false);
+  assert.ifError(err);
 });
 
 // Tab Complete will not break in an object literal
@@ -38,7 +26,7 @@ putIn.run([
   'var inner = {',
   'one:1'
 ]);
-testMe.complete('inner.o', getDoNotCallFunction());
+testMe.complete('inner.o', getNoResultsFunction());
 
 testMe.complete('console.lo', common.mustCall(function(error, data) {
   assert.deepStrictEqual(data, [['console.log'], 'console.lo']);
@@ -58,7 +46,7 @@ putIn.run([
   '?',
   '{one: 1} : '
 ]);
-testMe.complete('inner.o', getDoNotCallFunction());
+testMe.complete('inner.o', getNoResultsFunction());
 
 putIn.run(['.clear']);
 
@@ -74,7 +62,7 @@ testMe.complete('inner.o', common.mustCall(function(error, data) {
 // When you close the function scope tab complete will not return the
 // locally scoped variable
 putIn.run(['};']);
-testMe.complete('inner.o', getDoNotCallFunction());
+testMe.complete('inner.o', getNoResultsFunction());
 
 putIn.run(['.clear']);
 
@@ -129,7 +117,7 @@ putIn.run([
   ' one:1',
   '};'
 ]);
-testMe.complete('inner.o', getDoNotCallFunction());
+testMe.complete('inner.o', getNoResultsFunction());
 
 putIn.run(['.clear']);
 
@@ -142,7 +130,7 @@ putIn.run([
   ' one:1',
   '};'
 ]);
-testMe.complete('inner.o', getDoNotCallFunction());
+testMe.complete('inner.o', getNoResultsFunction());
 
 putIn.run(['.clear']);
 
@@ -156,7 +144,7 @@ putIn.run([
   ' one:1',
   '};'
 ]);
-testMe.complete('inner.o', getDoNotCallFunction());
+testMe.complete('inner.o', getNoResultsFunction());
 
 putIn.run(['.clear']);
 
@@ -254,6 +242,21 @@ testMe.complete('obj.', common.mustCall(function(error, data) {
 putIn.run(['.clear']);
 putIn.run(['function a() {}']);
 
-testMe.complete('a().b.', common.mustCall((error, data) => {
-  assert.deepStrictEqual(data, [[], undefined]);
+testMe.complete('a().b.', getNoResultsFunction());
+
+// Works when prefixed with spaces
+putIn.run(['.clear']);
+putIn.run(['var obj = {1:"a","1a":"b",a:"b"};']);
+
+testMe.complete(' obj.', common.mustCall((error, data) => {
+  assert.strictEqual(data[0].indexOf('obj.1'), -1);
+  assert.strictEqual(data[0].indexOf('obj.1a'), -1);
+  assert.notStrictEqual(data[0].indexOf('obj.a'), -1);
+}));
+
+// Works inside assignments
+putIn.run(['.clear']);
+
+testMe.complete('var log = console.lo', common.mustCall((error, data) => {
+  assert.deepStrictEqual(data, [['console.log'], 'console.lo']);
 }));